Research On Frictional Tactile Perception Of Rough Surfaces

Like other senses,touch has a complex and detailed information processing mechanism.In the process of tactile perception,it involves the collection of tactile information,the transmission of nerve signals,the processing and analysis of brain and so on.In this paper,the frictional vibration characteristics of skin touching rough surface were studied from the perspective of tribology.By combining EEG and NMR methods,the corresponding processing areas of cerebral cortex were analyzed and studied when the human body touched samples with different surface roughness,and the EEG signals in this area were analyzed.The proximal stimulation of tactile receptors was correlated with brain cognition.In order to provide theoretical support for the quantitative characterization of object surface roughness perception,the mechanism and principle of human body’s contact perception neural processing on material surface roughness were explored,and the real brain response of human body when contacting samples with different roughness was studied.The main research results are as follows:1.Cognitive behavioral studies show that surfaces with large roughness have a strong sense of roughness,a low sense of adhesion and a low sense of meticulousness.Roughness,stickiness and fineness affect the contact comfort together,and greater roughness,stickiness and lower fineness will reduce the comfort.The research of finger friction tactile perception shows that the vertical deviation and power spectrum center of gravity increase with the increase of velocity,and the friction coefficient is less affected by the velocity.Vertical deviation,friction coefficient and power spectrum center of gravity can be used to quantitatively characterize the roughness,adhesion and meticulousness of the material surface.The larger the vertical deviation,the stronger the rough feeling,the greater the friction coefficient,the stronger the adhesive feeling,the larger the power spectrum center of gravity,the better the delicate feeling.2.The MRI study showed that when the touch perception of rough surface,there were activation reactions in both the left and right brain regions of the brain,and the positive activation was mainly in the left brain.The brain tissue regions activated by rough surfaces were mainly located in the left posterior central gyrus,inferior parietal lobule,superior marginal gyrus,anterior central gyrus and superior temporal gyrus,and the posterior central gyrus was dominant.The rough surface stimulated the primary somatosensory cortex,the secondary somatosensory cortex,the primary motor cortex and the secondary motor cortex,and the primary somatosensory cortex was the dominant part.With the decrease of surface roughness,the activated brain area and intensity decreased first and then increased,among which the activated brain area of sample 3# was the smallest,the activation intensity of sample 2# was the weakest,and the activation area and intensity of sample 5# were the largest.The activation area and intensity of the brain are affected by the physical properties of the material surface,which can be used to represent comfort,and they are negatively correlated.3.The ERP whole-brain topographic map showed that the activation locations of tactile perception were mainly concentrated in the central sulcus area of the left and right brain,which was basically consistent with the MRI data.The P100,P200 and P300 components of ERP curves were induced by finger touching the sample surface with different roughness.The peak value of P200 induced by different rough surfaces was significantly different,which decreased gradually from 1# to 4#,indicating that the peak value of P200 was significantly related to the surface roughness of the material,and the decrease of the response strength of brain neurons to the roughness of the material surface would lead to the decrease of the peak value of P200.The peak value of P100 induced by different rough surfaces showed no significant difference until P200,indicating that the perception of brain neurons on rough surfaces started from P100 and reached the peak value around P200.The P300 peak value induced by different rough surfaces was significantly different,which gradually decreased from 1# to 4# sample,indicating that the roughness difference between the surface and the standard stimulus gradually decreased,which would cause the brain to need more attention resources in tactile perception judgment.The P300 latency of 3# and 4# samples is significantly later than that of 1# and 2# samples,indicating that the samples with larger roughness are easier to be recognized.This paper has 40 figures,10 tables and 91 references.